1. Technical Field
The embodiments described herein relate to electronic circuits, and more particularly, to a processing chip for a digital microphone and related input circuit and a digital microphone.
2. Related Art
Digital microphone is the electro-acoustic component of microphone for directly outputting the digital pulse signal. Digital microphone has the characteristics of high anti-interference capacities, high integration, and ease of use. As a result, it has been widely used for power and size sensitive portable devices.
FIG. 1 is a structure diagram showing a digital microphone under the existing technologies. The digital microphone includes a microphone 11 and a processing chip 12, in which the processing chip 12 may include an input circuit 120, an amplifier circuit 121 and an analog-to-digital conversion circuit 122. In particular, the microphone 11 converts sound signals into analog electronic signals and sends the analog electronic signals to the processing chip 12. Then the input circuit 120 in the processing chip 12 receives the analog electrical signals and the amplifier circuit 121 amplifies the analog signals, and the analog-to-digital conversion circuit 122 converts the amplified analog electronic signals into digital signals and then outputs the digital signals.
Under the existing technologies, the analog electronic signals outputted by the microphone 11 carry high-frequency interference signals, the analog electronic signals outputted to the amplifier circuit 121 by the input circuit 120 carry relatively strong high-frequency interference signals, resulting in poor anti-high-frequency interference capabilities for the processing chip 12. Moreover, the power supply of the input circuit 120 also carries high-frequency interference signals, resulting in low high-frequency power supply rejection ratio for the input circuit 120.